1. Field of the Invention
The present invention is generally directed to apparatuses, systems, and methods associated with substrate processing. Certain aspects of the present invention are directed to a load lock apparatus, systems, and methods useable in semiconductor wafer processing and/or processing of other substrates, such as those intended for flat panel displays. Other aspects may be related to processing chambers for substrate processing.
2. Background of the Invention
In order to produce semiconductor wafers, manufactures start with an unprocessed substrate and perform various processing steps to convert the substrate to a semiconductor wafer. These process may include scrubbing the substrate to provide a clean surface, etching, depositing, or plating the substrate, and cooling the substrate to produce the finished semiconductor wafer. Some of these steps may be grouped together and performed within a single semiconductor tool.
A semiconductor tool may include a central transfer chamber with a plurality of processing chambers mounted around the periphery of the central transfer chamber. A robot arm may be located inside the central transfer chamber to move the substrate from one processing station to the next. In general, most, if not all of the processing stations and the central transfer chamber are maintained at or near vacuum conditions. The vacuum condition provides many benefits including the prevention of undesirable particles or other impurities being deposited onto the substrate.
For most semiconductor tools, the supply of substrates is maintained outside of the semiconductor tool in an area at or near atmospheric pressure. As such, semiconductor manufacturing facilities typically include an apparatus that allows transfer of substrates from this atmospheric condition to the vacuum condition of the semiconductor tool. Load lock apparatuses have been used to allow this type of transfer.
Some conventional load lock apparatuses generally include two gate valves, one being configured to open into the central transfer chamber and the other being configured to open to allow insertion of the substrates from a storage location. A vacuum pump attached to the load lock provides a vacuum condition after the substrates have been inserted into the load lock apparatus. Once vacuum is provided in the load lock apparatus, the gate valve leading to the central transfer chamber is opened and the substrates can be moved from the load lock into the central chamber. After all of the processing has occurred, the semiconductor wafers (substrates) are moved back into the load lock apparatus. At this time, the vacuum is removed, the load lock is returned to atmospheric pressure, and the semiconductor wafers may be removed.
Current load locks typically are designed to transfer several substrates at a single time into the semiconductor tool. These load locks typically have a volume between 6 and 10 liters. Because the volume of the load locks are large, it can take several seconds or even minutes to cycle between atmospheric pressure and vacuum conditions. This, in turn, limits the number of semiconductor wafers that can be produced with the semiconductor tool. For example, typical through rates of semiconductor tools range between 100 to 150 semiconductor wafers per hour, and attempts to improve these rates are limited by the pressure cycling of the load locks. In addition, these load locks often require large amounts of gas to be added or withdrawn quickly, which creates potential problems of damaging or contaminating the wafers.
One possible approach to increasing the number of semiconductor wafers produced per hour is to decrease the size of load lock and thereby reduce the pressure cycling time. Decreasing the size of the load lock, however, presents a number of technical challenges.
The present invention is directed to systems, apparatus, and methods that may obviate one or more of the limitations of the related art. In particular, the present invention could be directed to systems and methods that might be used in substrate processing for transferring processed and/or unprocessed substrates, such as wafers or substrates intended for flat panel display.
One aspect relates to a system comprising a load lock apparatus having an interior configured to receive an object. At least one inlet valve may be flow coupled to the interior of the load lock apparatus, and at least one outlet valve may also be flow coupled to the interior of the load lock apparatus. A controller may be configured to selectively control opening and closing of the at least one inlet valve.
The controller may be configured to open the at least one inlet valve and leave the one inlet valve open while the at least one outlet valve is closed for a predetermined period of time so as to substantially equilibrate pressure in the interior with pressure exterior of the load lock apparatus. The controller may also be configured to open the at least one outlet valve after the predetermined period of time to prevent over pressurization of the interior.
The load lock apparatus may comprise at least one opening permitting insertion of the object into the interior of the apparatus. Optionally, the load lock apparatus may further comprise at least one gate valve configured to selectively close the opening. The controller may be configured to open the at least one gate valve after the at least one outlet valve is opened.
The predetermined period of time may range from about 0.1 seconds to about 4 seconds, such as, for example, about 1.5 seconds.
In another aspect, there is a system comprising a load lock apparatus including an interior configured to receive an object and a gas supply flow path configured to provide flow of gas from a gas source to the interior of the load lock apparatus. At least one inlet valve may be configured to control flow of gas through the gas supply flow path. A pressure limiter (e.g., pressure relief valve, pressure switch, mass flow controller, or other pressure limiter) may be associated with the gas supply flow path to maintain pressure of gas flowing to the interior of the load lock apparatus below a predetermined maximum pressure. The predetermined maximum pressure may be, for example, greater than pressure external to the load lock apparatus.
Yet another aspect relates to a system comprising a load lock apparatus including an interior configured to receive an object, a gas supply flow path configured to provide flow of gas from a gas source to the interior of the load lock apparatus, at least one inlet valve configured to control flow of gas through the gas supply flow path, and a gas outlet flow path configured to provide flow of gas from the interior of the load lock apparatus. At least one outlet valve may be configured to control flow of gas through the gas outlet flow path. A check valve may be associated with the gas outlet flow path downstream from the at least one outlet valve to prevent backflow of gas while the at least one outlet valve is open.
In another aspect, there is a system comprising a load lock apparatus including an interior, at least first and second inlets arranged to provide flow of gas to the interior, and an object receiving mechanism located within the interior to receive an object. The first inlet may be arranged above the object receiving mechanism and the second inlet may be arranged below the object receiving mechanism. A gas supply flow path may be configured to provide flow of gas from a gas source to the interior of the load lock apparatus via the at least first and second inlets. At least one inlet valve may be configured to control flow of gas through the gas supply flow path.
The at least first and second inlets may further comprise a third inlet arranged below the object receiving mechanism.
The at least one inlet valve may comprise a first inlet valve and a second inlet valve. The first inlet valve may be flow coupled to the first inlet and the second inlet valve may be flow coupled to the second inlet. Alternatively, the at least one inlet valve may comprise a primary valve and a plurality of secondary valves. The primary valve may be flow coupled to the secondary valves (e.g., upstream of the secondary valves) and each of the secondary valves may be flow coupled to one of the at least first and second inlets.
A controller may be configured to selectively open and close the primary valve and the plurality of secondary valves. For example, the controller may be configured to selectively open and close the primary valve and plurality of secondary valves independent of each other.
In yet another aspect, there is a system comprising a load lock apparatus having an interior, a plurality of inlets arranged to provide flow of gas to the interior, and an object receiving mechanism located within the interior to receive the object. A gas supply flow path may be configured to provide flow of gas from a gas source to the interior of the load lock apparatus via the plurality of inlets. A plurality of inlet valves may be provided. Each of the plurality of inlet valves may be associated with a respective one of the plurality of inlets to control flow of gas through the plurality of inlets.
A primary inlet valve may be provided, wherein the plurality of inlet valves are secondary inlet valves flow coupled to the primary inlet valve (e.g., downstream of the primary inlet valve). A controller may be configured to control the opening and closing of the primary inlet valve and the secondary inlet valves.
A further aspect relates to a system comprising a load lock apparatus including a chamber having an interior, at least one opening permitting placement of an object into the chamber, and at least one gate valve configured to selectively close the at least one opening. A gas supply flow path may be configured to provide flow of gas from a gas source to the chamber of the load lock apparatus. At least one inlet valve may be configured to provide flow of gas through the gas supply flow path. At least one outlet valve may be flow coupled to the chamber of the load lock apparatus. A controller may be configured to selectively control opening and closing of the at least one inlet valve and the at least one outlet valve, for example, to control the inlet and outlet valves such that the inlet and outlet valves are simultaneously in an open position for at least a period of time when the at least one gate valve is in a closed position closing the at least one opening. This may allow purging of contaminants from the interior.
In another aspect, there is a system comprising a load lock apparatus having a chamber including an interior, at least one opening permitting placement of an object into the chamber, and at least one gate valve configured to selectively close the at least one opening. A gas supply flow path may be configured to provide flow of gas from a gas source to the chamber of the load lock apparatus. At least one inlet valve may be configured to control flow of gas through the gas supply flow path. At least one outlet valve may be flow coupled to the chamber of the load lock apparatus. A controller may be provided to control the at least one inlet valve and the at least one outlet valve so as to provide a high flow rate of gas into the chamber for at least a period of time while the at least one gate valve is in a closed position and to provide a low flow rate of gas into the chamber for at least a period of time while the at least one gate valve is in an open position.
The at least one inlet valve may comprise a first inlet valve and a second inlet valve, and the controller may be configured to control the first and second inlet valves and the outlet valve such that gas flow is provided through the first inlet valve while the at least one outlet valve is closed and gas flow is provided through the second inlet valve while the at least one outlet valve is open.
A further aspect relates to an apparatus for use in substrate processing comprising a chamber having an interior, at least one opening permitting placement of an object into the chamber, and at least one exhaust port. The apparatus may also include at least one gate valve configured to selectively close the at least one opening, an exhaust flow path flow communicating with the interior of the chamber via the at least one exhaust port, a vacuum pump associated with the exhaust flow path to cause vacuum flow in the exhaust flow path. An object receiving mechanism may be located within the chamber, and may be configured to be movable in the interior so as to adjust conductance of exhaust flow from the interior to the exhaust flow path via the at least one exhaust port. As used herein, adjusting conductance relates to varying the amount of gas flow restriction in an area, wherein such varying could take place while gas is flowing through the area (e.g., gas throttling) or while gas is not flowing through the area. A controller may be provided and configured to control movement of the object receiving mechanism to adjust the throttling of exhaust flow from the interior.
The chamber may include a sub-chamber and the exhaust port may be located in the sub-chamber. In this arrangement, movement of the object receiving mechanism may adjust the distance between a lower surface of the object receiving mechanism and an upper surface of the sub-chamber.
The object receiving mechanism may be configured to increase the throttling when the object receiving mechanism is in a lowered position and to decrease the throttling when the object receiving mechanism is in a raised positioned.
The object receiving mechanism may comprise a movement mechanism chosen from a linear actuator, a hydraulic piston, and a pneumatic piston. The object receiving mechanism may comprise a vacuum hold down system to hold an object to the object receiving mechanism when the object receiving mechanism is moved. For example, the object receiving mechanism may comprise a hollow shaft connected to a plate member having at least one through hole, and the vacuum hold down system may comprise a vacuum flow path configured to place the hollow shaft in flow communication with the vacuum pump. The plate member may further include a plurality of raised portions to assist in securing the object to the plate member. The object receiving mechanism may comprise a plurality of receiving portions, each of which is configured to receive the object.
The load lock apparatus may also include a station supported by the chamber. The station may be configured to receive the object prior to placement of the object within the chamber and/or after removal of the object from the chamber. The station may be configured to allow cooling of the object after removal from the chamber.
In yet another aspect, there is a method of adjusting pressure in an interior of a load lock apparatus to be substantially at equilibrium with pressure external to the load lock apparatus. The load lock apparatus may be associated with at least one inlet valve flow coupled to the interior of the load lock apparatus, and at least one outlet valve flow coupled to the interior of the load lock apparatus. The method includes opening the inlet valve so as to flow gas at a predetermined flow rate into the interior of the load lock apparatus, maintaining the outlet valve in a closed position for a predetermined period of time after the opening of the inlet valve so as to enable pressure in the interior to approach pressure external to the load lock apparatus, and opening the at least one outlet valve after the predetermined period of time elapses so as to prevent over pressurization in the interior.
The load lock apparatus may be further associated with a gas supply flow path configured to provide flow of gas from a gas source to the interior of the load lock apparatus through the inlet valve. The method may further include supplying gas from the gas source to the interior of the load lock apparatus.
Another aspect relates to a method of removing contaminants from a load lock apparatus. The load lock apparatus may comprise a chamber having an interior. The load lock apparatus may be associated with at least one inlet valve flow coupled to the interior of the load lock apparatus, and at least one outlet valve flow coupled to the interior of the load lock apparatus. The method includes opening the inlet valve so as to flow gas at a predetermined flow rate into the interior of the load lock apparatus, opening the at least one outlet valve so as to flow gas out of the interior of the load lock apparatus, and maintaining the at least one inlet valve and the at least one outlet valve simultaneously open for at least a period of time while the gate valve is in a closed position so as to allow removal of contaminants from the interior of the load lock apparatus.
Yet another aspect relates to a method of purging a load lock apparatus. The load lock apparatus may comprise a chamber having an interior, an opening permitting placement of an object into the chamber, and a gate valve configured to selectively close the opening. The load lock apparatus may be associated with at least one inlet valve flow coupled to the interior of the load lock apparatus, and at least one outlet valve flow coupled to the interior of the load lock apparatus. The method includes opening the at least one inlet valve to provide a high flow rate of gas into the interior, maintaining the high flow rate of gas into the interior for at least a period of time while the gate valve is in a closed position closing the opening, opening the at least one outlet valve, changing the flow rate of the gas from a high flow rate of gas to a low flow rate of gas into the interior for at least a period of time while the gate valve is in the closed position, placing the gate valve in an open position, and maintaining the low flow rate of gas into the interior for at least a period of time after placing the gate valve in the open position.
The at least one inlet valve may comprise a first inlet valve and second inlet valve. Opening of the at least one inlet valve to provide high flow rate of gas into the interior may comprise opening the first inlet valve to provide the high flow rate of gas into the interior. Changing the high flow rate of gas to the low flow rate of gas may comprise closing the first inlet valve and opening the second inlet valve.
In an even further aspect, there is a method of controlling the rate of gas exhaust in a load lock apparatus. The load lock apparatus may comprise a chamber including an interior, at least one exhaust port, an exhaust flow path flow communicating with the interior of the chamber via the at least one exhaust port, and an object receiving mechanism located within the chamber. The object receiving mechanism may be configured to be movable in the interior. The method comprises causing vacuum flow from the interior to the exhaust flow path via the at least one exhaust port, and moving the object receiving mechanism within the interior to adjust the throttling of the vacuum flow from the interior to the exhaust flow path via the at least one exhaust port.
The moving of the object receiving mechanism within the interior to adjust the throttling may include moving the object receiving mechanism away from the at least one exhaust port to decreases the throttling of the vacuum flow. Alternatively, or in addition, the object receiving mechanism may be moved towards the at least one exhaust port to increase the throttling of the vacuum flow.
Each of the described systems, apparatuses, and methods may be used in substrate processing. For example, a transfer chamber may be arranged to allow transfer of the object from the transfer chamber to the interior of the load lock apparatus via an opening. The transfer chamber may be at vacuum pressure. A transfer mechanism may also be provided to allow transfer of the object to the interior of the load lock apparatus through the at least one opening from an environment at atmospheric pressure external to the load lock apparatus. In addition, the object may be a processed substrate and/or an unprocessed substrate. For example, the substrate could be intended for use in a semiconductor and/or a flat panel display.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.